X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlport.pod;h=ffd7c863b32eede5b1c99252031f2d742f79e90c;hb=28b41a8090d259cff9b1dd87c0c53b3c4a31e822;hp=d589423c0d7a8a65a2f5b8a1877d7c29f1be73d5;hpb=1d65be3a6a280824a66294902ffa798d54d7fac2;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlport.pod b/pod/perlport.pod index d589423..ffd7c86 100644 --- a/pod/perlport.pod +++ b/pod/perlport.pod @@ -188,12 +188,12 @@ The Unix column assumes that you are not accessing a serial line "\n", and "\n" on output becomes CRLF. These are just the most common definitions of C<\n> and C<\r> in Perl. -There may well be others. For example, on an EBCDIC implementation such -as z/OS or OS/400 the above material is similar to "Unix" but the code -numbers change: +There may well be others. For example, on an EBCDIC implementation +such as z/OS (OS/390) or OS/400 (using the ILE, the PASE is ASCII-based) +the above material is similar to "Unix" but the code numbers change: - LF eq \025 eq \x15 eq chr(21) eq CP-1047 21 - LF eq \045 eq \x25 eq \cU eq chr(37) eq CP-0037 37 + LF eq \025 eq \x15 eq \cU eq chr(21) eq CP-1047 21 + LF eq \045 eq \x25 eq chr(37) eq CP-0037 37 CR eq \015 eq \x0D eq \cM eq chr(13) eq CP-1047 13 CR eq \015 eq \x0D eq \cM eq chr(13) eq CP-0037 13 @@ -224,6 +224,10 @@ them in big-endian mode. To avoid this problem in network (socket) connections use the C and C formats C and C, the "network" orders. These are guaranteed to be portable. +As of perl 5.9.2, you can also use the C> and C> modifiers +to force big- or little-endian byte-order. This is useful if you want +to store signed integers or 64-bit integers, for example. + You can explore the endianness of your platform by unpacking a data structure packed in native format such as: @@ -404,10 +408,12 @@ interaction. A program requiring a command line interface might not work everywhere. This is probably for the user of the program to deal with, so don't stay up late worrying about it. -Some platforms can't delete or rename files held open by the system. -Remember to C files when you are done with them. Don't -C or C an open file. Don't C or C a -file already tied or opened; C or C it first. +Some platforms can't delete or rename files held open by the system, +this limitation may also apply to changing filesystem metainformation +like file permissions or owners. Remember to C files when you +are done with them. Don't C or C an open file. Don't +C or C a file already tied or opened; C or C +it first. Don't open the same file more than once at a time for writing, as some operating systems put mandatory locks on such files. @@ -446,7 +452,12 @@ C instead. Don't count on per-program environment variables, or per-program current directories. -Don't count on specific values of C<$!>. +Don't count on specific values of C<$!>, neither numeric nor +especially the strings values-- users may switch their locales causing +error messages to be translated into their languages. If you can +trust a POSIXish environment, you can portably use the symbols defined +by the Errno module, like ENOENT. And don't trust on the values of C<$!> +at all except immediately after a failed system call. =head2 Command names versus file pathnames @@ -480,6 +491,42 @@ To convert $Config{perlpath} to a file pathname, say: if ($^O ne 'VMS') {$thisperl .= $Config{_exe} unless $thisperl =~ m/$Config{_exe}$/i;} +=head2 Networking + +Don't assume that you can reach the public Internet. + +Don't assume that there is only one way to get through firewalls +to the public Internet. + +Don't assume that you can reach outside world through any other port +than 80, or some web proxy. ftp is blocked by many firewalls. + +Don't assume that you can send email by connecting to the local SMTP port. + +Don't assume that you can reach yourself or any node by the name +'localhost'. The same goes for '127.0.0.1'. You will have to try both. + +Don't assume that the host has only one network card, or that it +can't bind to many virtual IP addresses. + +Don't assume a particular network device name. + +Don't assume a particular set of ioctl()s will work. + +Don't assume that you can ping hosts and get replies. + +Don't assume that any particular port (service) will respond. + +Don't assume that Sys::Hostname() (or any other API or command) +returns either a fully qualified hostname or a non-qualified hostname: +it all depends on how the system had been configured. Also remember +things like DHCP and NAT-- the hostname you get back might not be very +useful. + +All the above "don't":s may look daunting, and they are -- but the key +is to degrade gracefully if one cannot reach the particular network +service one wants. Croaking or hanging do not look very professional. + =head2 Interprocess Communication (IPC) In general, don't directly access the system in code meant to be @@ -564,16 +611,24 @@ work with any DBM module. See L for more details. The system's notion of time of day and calendar date is controlled in widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>, and even if it is, don't assume that you can control the timezone through -that variable. +that variable. Don't assume anything about the three-letter timezone +abbreviations (for example that MST would be the Mountain Standard Time, +it's been known to stand for Moscow Standard Time). If you need to +use timezones, express them in some unambiguous format like the +exact number of minutes offset from UTC, or the POSIX timezone +format. Don't assume that the epoch starts at 00:00:00, January 1, 1970, -because that is OS- and implementation-specific. It is better to store a date -in an unambiguous representation. The ISO-8601 standard defines -"YYYY-MM-DD" as the date format. A text representation (like "1987-12-18") -can be easily converted into an OS-specific value using a module like -Date::Parse. An array of values, such as those returned by -C, can be converted to an OS-specific representation using -Time::Local. +because that is OS- and implementation-specific. It is better to +store a date in an unambiguous representation. The ISO 8601 standard +defines YYYY-MM-DD as the date format, or YYYY-MM-DDTHH-MM-SS +(that's a literal "T" separating the date from the time). +Please do use the ISO 8601 instead of making us to guess what +date 02/03/04 might be. ISO 8601 even sorts nicely as-is. +A text representation (like "1987-12-18") can be easily converted +into an OS-specific value using a module like Date::Parse. +An array of values, such as those returned by C, can be +converted to an OS-specific representation using Time::Local. When calculating specific times, such as for tests in time or date modules, it may be appropriate to calculate an offset for the epoch. @@ -585,6 +640,9 @@ The value for C<$offset> in Unix will be C<0>, but in Mac OS will be some large number. C<$offset> can then be added to a Unix time value to get what should be the proper value on any system. +On Windows (at least), you shouldn't pass a negative value to C or +C. + =head2 Character sets and character encoding Assume very little about character sets. @@ -611,6 +669,25 @@ or at least more convenient and native-friendly for non-English users. The system affects character sets and encoding, and date and time formatting--amongst other things. +If you really want to be international, you should consider Unicode. +See L and L for more information. + +If you want to use non-ASCII bytes (outside the bytes 0x00..0x7f) in +the "source code" of your code, to be portable you have to be explicit +about what bytes they are. Someone might for example be using your +code under a UTF-8 locale, in which case random native bytes might be +illegal ("Malformed UTF-8 ...") This means that for example embedding +ISO 8859-1 bytes beyond 0x7f into your strings might cause trouble +later. If the bytes are native 8-bit bytes, you can use the C +pragma. If the bytes are in a string (regular expression being a +curious string), you can often also use the C<\xHH> notation instead +of embedding the bytes as-is. If they are in some particular legacy +encoding (ether single-byte or something more complicated), you can +use the C pragma. (If you want to write your code in UTF-8, +you can use either the C pragma, or the C pragma.) +The C and C pragmata are available since Perl 5.6.0, and +the C pragma since Perl 5.8.0. + =head2 System Resources If your code is destined for systems with severely constrained (or @@ -672,12 +749,14 @@ Be careful in the tests you supply with your module or programs. Module code may be fully portable, but its tests might not be. This often happens when tests spawn off other processes or call external programs to aid in the testing, or when (as noted above) the tests -assume certain things about the filesystem and paths. Be careful -not to depend on a specific output style for errors, such as when -checking C<$!> after a system call. Some platforms expect a certain -output format, and perl on those platforms may have been adjusted -accordingly. Most specifically, don't anchor a regex when testing -an error value. +assume certain things about the filesystem and paths. Be careful not +to depend on a specific output style for errors, such as when checking +C<$!> after a failed system call. Using C<$!> for anything else than +displaying it as output is doubtful (though see the Errno module for +testing reasonably portably for error value). Some platforms expect +a certain output format, and Perl on those platforms may have been +adjusted accordingly. Most specifically, don't anchor a regex when +testing an error value. =head1 CPAN Testers @@ -832,8 +911,9 @@ Win32::GetOSVersion(). For example: print +('3.1','95','NT')[$os_version_info[4]],"\n"; } -There are also Win32::IsWinNT() and Win32::IsWin95(), tryC. -The very portable POSIX::uname() will work too: +There are also Win32::IsWinNT() and Win32::IsWin95(), try C, +and as of libwin32 0.19 (not part of the core Perl distribution) +Win32::GetOSName(). The very portable POSIX::uname() will work too: c:\> perl -MPOSIX -we "print join '|', uname" Windows NT|moonru|5.0|Build 2195 (Service Pack 2)|x86 @@ -1026,7 +1106,7 @@ native formats. What C<\n> represents depends on the type of file opened. It usually represents C<\012> but it could also be C<\015>, C<\012>, C<\015\012>, -C<\000>, C<\040>, or nothing depending on the file organiztion and +C<\000>, C<\040>, or nothing depending on the file organization and record format. The VMS::Stdio module provides access to the special fopen() requirements of files with unusual attributes on VMS. @@ -1092,13 +1172,6 @@ contain a slash character cannot be processed. Such files must be renamed before they can be processed by Perl. Note that VOS limits file names to 32 or fewer characters. -Perl on VOS can be built using two different compilers and two different -versions of the POSIX runtime. The recommended method for building full -Perl is with the GNU C compiler and the generally-available version of -VOS POSIX support. See F (installed as L) for -restrictions that apply when Perl is built using the VOS Standard C -compiler or the alpha version of VOS POSIX support. - The value of C<$^O> on VOS is "VOS". To determine the architecture that you are running on without resorting to loading all of C<%Config> you can examine the content of the @INC array like so: @@ -1110,19 +1183,6 @@ can examine the content of the @INC array like so: die; } - if (grep(/860/, @INC)) { - print "This box is a Stratus XA/R!\n"; - - } elsif (grep(/7100/, @INC)) { - print "This box is a Stratus HP 7100 or 8xxx!\n"; - - } elsif (grep(/8000/, @INC)) { - print "This box is a Stratus HP 8xxx!\n"; - - } else { - print "This box is a Stratus 68K!\n"; - } - Also see: =over 4 @@ -1155,7 +1215,9 @@ Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390 systems). On the mainframe perl currently works under the "Unix system services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater). -See L for details. +See L for details. Note that for OS/400 there is also a port of +Perl 5.8.1/5.9.0 or later to the PASE which is ASCII-based (as opposed to +ILE which is EBCDIC-based), see L. As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix sub-systems do not support the C<#!> shebang trick for script invocation. @@ -1398,7 +1460,7 @@ as well as from CPAN. =item * -Plan 9, F +S, F =back @@ -1467,12 +1529,6 @@ suffixes. C<-S> is meaningless. (Win32) C<-x> (or C<-X>) determine if a file has an executable file type. (S) -=item alarm SECONDS - -=item alarm - -Not implemented. (Win32) - =item binmode FILEHANDLE Meaningless. (S, S) @@ -1501,30 +1557,30 @@ in the SYSTEM environment settings. (Cygwin) =item chown LIST -Not implemented. (S, Win32, Plan9, S, VOS) +Not implemented. (S, Win32, S, S) Does nothing, but won't fail. (Win32) +A little funky, because VOS's notion of ownership is a little funky (VOS). + =item chroot FILENAME =item chroot -Not implemented. (S, Win32, VMS, Plan9, S, VOS, VM/ESA) +Not implemented. (S, Win32, VMS, S, S, VOS, VM/ESA) =item crypt PLAINTEXT,SALT May not be available if library or source was not provided when building perl. (Win32) -Not implemented. (VOS) - =item dbmclose HASH -Not implemented. (VMS, Plan9, VOS) +Not implemented. (VMS, S, VOS) =item dbmopen HASH,DBNAME,MODE -Not implemented. (VMS, Plan9, VOS) +Not implemented. (VMS, S, VOS) =item dump LABEL @@ -1566,7 +1622,7 @@ Available only on Windows NT (not on Windows 95). (Win32) =item fork -Not implemented. (S, AmigaOS, S, VOS, VM/ESA) +Not implemented. (S, AmigaOS, S, VM/ESA, VMS) Emulated using multiple interpreters. See L. (Win32) @@ -1579,11 +1635,11 @@ Not implemented. (S, S) =item getpgrp PID -Not implemented. (S, Win32, VMS, S, VOS) +Not implemented. (S, Win32, VMS, S) =item getppid -Not implemented. (S, Win32, VMS, S) +Not implemented. (S, Win32, S) =item getpriority WHICH,WHO @@ -1601,7 +1657,7 @@ Not implemented. (S, Win32, VMS, S) =item getnetbyname NAME -Not implemented. (S, Win32, Plan9) +Not implemented. (S, Win32, S) =item getpwuid UID @@ -1615,7 +1671,7 @@ Not implemented. (S, Win32, VMS, S) =item getnetbyaddr ADDR,ADDRTYPE -Not implemented. (S, Win32, Plan9) +Not implemented. (S, Win32, S) =item getprotobynumber NUMBER @@ -1633,37 +1689,42 @@ Not implemented. (S, Win32, VM/ESA) Not implemented. (S, Win32, VMS, VM/ESA) +=item gethostbyname + +C does not work everywhere: you may have +to use C. (S, S) + =item gethostent Not implemented. (S, Win32) =item getnetent -Not implemented. (S, Win32, Plan9) +Not implemented. (S, Win32, S) =item getprotoent -Not implemented. (S, Win32, Plan9) +Not implemented. (S, Win32, S) =item getservent -Not implemented. (Win32, Plan9) +Not implemented. (Win32, S) =item sethostent STAYOPEN -Not implemented. (S, Win32, Plan9, S) +Not implemented. (S, Win32, S, S) =item setnetent STAYOPEN -Not implemented. (S, Win32, Plan9, S) +Not implemented. (S, Win32, S, S) =item setprotoent STAYOPEN -Not implemented. (S, Win32, Plan9, S) +Not implemented. (S, Win32, S, S) =item setservent STAYOPEN -Not implemented. (Plan9, Win32, S) +Not implemented. (S, Win32, S) =item endpwent @@ -1679,19 +1740,19 @@ Not implemented. (S, Win32) =item endnetent -Not implemented. (S, Win32, Plan9) +Not implemented. (S, Win32, S) =item endprotoent -Not implemented. (S, Win32, Plan9) +Not implemented. (S, Win32, S) =item endservent -Not implemented. (Plan9, Win32) +Not implemented. (S, Win32) =item getsockopt SOCKET,LEVEL,OPTNAME -Not implemented. (Plan9) +Not implemented. (S) =item glob EXPR @@ -1751,7 +1812,7 @@ Return values (especially for device and inode) may be bogus. (Win32) =item msgrcv ID,VAR,SIZE,TYPE,FLAGS -Not implemented. (S, Win32, VMS, Plan9, S, VOS) +Not implemented. (S, Win32, VMS, S, S, VOS) =item open FILEHANDLE,EXPR @@ -1793,7 +1854,7 @@ Not implemented. (S, Win32, VMS, S, VOS) =item setgrent -Not implemented. (S, MPE/iX, VMS, Win32, VMS, S) +Not implemented. (S, MPE/iX, VMS, Win32, S, VOS) =item setpgrp PID,PGRP @@ -1805,11 +1866,11 @@ Not implemented. (S, Win32, VMS, S, VOS) =item setpwent -Not implemented. (S, MPE/iX, Win32, S) +Not implemented. (S, MPE/iX, Win32, S, VOS) =item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL -Not implemented. (Plan9) +Not implemented. (S) =item shmctl ID,CMD,ARG @@ -1938,7 +1999,7 @@ Not useful. (S) Not implemented. (Older versions of VMS) -Truncation to zero-length only. (VOS) +Truncation to same-or-shorter lengths only. (VOS) If a FILEHANDLE is supplied, it must be writable and opened in append mode (i.e., use C<<< open(FH, '>>filename') >>> @@ -1968,7 +2029,7 @@ two seconds. (Win32) =item waitpid PID,FLAGS -Not implemented. (S, VOS) +Not implemented. (S) Can only be applied to process handles returned for processes spawned using C or pseudo processes created with C. (Win32) @@ -1981,6 +2042,10 @@ Not useful. (S) =over 4 +=item v1.49, 12 August 2002 + +Updates for VOS from Paul Green. + =item v1.48, 02 February 2001 Various updates from perl5-porters over the past year, supported @@ -2068,66 +2133,74 @@ First public release with perl5.005. =head1 Supported Platforms -As of June 2002 (the Perl release 5.8.0), the following platforms are +As of July 2002 (the Perl release 5.8.0), the following platforms are able to build Perl from the standard source code distribution available at http://www.cpan.org/src/index.html AIX BeOS + BSD/OS (BSDi) Cygwin DG/UX DOS DJGPP 1) DYNIX/ptx EPOC R5 FreeBSD + HI-UXMPP (Hitachi) (5.8.0 worked but we didn't know it) HP-UX IRIX Linux Mac OS Classic - Mac OS X (Darwin) + Mac OS X (Darwin) MPE/iX NetBSD NetWare NonStop-UX - ReliantUNIX (SINIX) + ReliantUNIX (formerly SINIX) OpenBSD - OpenVMS (VMS) + OpenVMS (formerly VMS) + Open UNIX (Unixware) (since Perl 5.8.1/5.9.0) OS/2 - POSIX-BC (BS2000) + OS/400 (using the PASE) (since Perl 5.8.1/5.9.0) + PowerUX + POSIX-BC (formerly BS2000) QNX Solaris - SUPER-UX - Tru64 UNIX (DEC OSF/1, Digital UNIX) + SunOS 4 + SUPER-UX (NEC) + Tru64 UNIX (formerly DEC OSF/1, Digital UNIX) UNICOS UNICOS/mk UTS VOS Win95/98/ME/2K/XP 2) WinCE - z/OS (OS/390) + z/OS (formerly OS/390) VM/ESA 1) in DOS mode either the DOS or OS/2 ports can be used - 2) compilers: Borland, Cygwin (GCC), MinGW (GCC), VC6 + 2) compilers: Borland, MinGW (GCC), VC6 The following platforms worked with the previous releases (5.6 and 5.7), but we did not manage either to fix or to test these in time for the 5.8.0 release. There is a very good chance that many of these -will work fine with the 5.8.0. The only one known for certain to be -broken for 5.8.0 is the AmigaOS. +will work fine with the 5.8.0. - AmigaOS + BSD/OS DomainOS Hurd LynxOS MachTen PowerMAX SCO SV - SunOS 4 SVR4 Unixware Windows 3.1 +Known to be broken for 5.8.0 (but 5.6.1 and 5.7.2 can be used): + + AmigaOS + The following platforms have been known to build Perl from source in the past (5.005_03 and earlier), but we haven't been able to verify their status for the current release, either because the @@ -2138,7 +2211,6 @@ of any trouble. 3b1 A/UX - BSD/OS ConvexOS CX/UX DC/OSx @@ -2159,23 +2231,21 @@ of any trouble. OpenSTEP Opus Plan 9 - PowerUX RISC/os - SCO ODT/OSR + SCO ODT/OSR Stellar SVR2 TI1500 TitanOS Ultrix Unisys Dynix - Unixware The following platforms have their own source code distributions and binaries available via http://www.cpan.org/ports/ Perl release - OS/400 5.005_02 + OS/400 (ILE) 5.005_02 Tandem Guardian 5.004 The following platforms have only binaries available via @@ -2195,11 +2265,13 @@ http://www.cpan.org/ports/index.html for binary distributions. =head1 SEE ALSO L, L, L, L, L, -L, L, L, L, L, L, -L, L, L, L, L, -L, L, L, L, L, -L, L, L, L, -L, L, L, L, and L. +L, L, L, L, L, +L, L, L, L, L, +L, L, L, L, L, +L, L, L, L, +L, L, L, L, +L, L, L, L, +L, and L. =head1 AUTHORS / CONTRIBUTORS @@ -2213,7 +2285,7 @@ Andy Dougherty , Dominic Dunlop , Neale Ferguson , David J. Fiander , -Paul Green , +Paul Green , M.J.T. Guy , Jarkko Hietaniemi , Luther Huffman ,